The minerals zinc, iron and copper regulate the expression of specific proteins, especially those that ensure cells receive minerals/involved in preventing toxicity. The question is how either excess copper or zinc WITH iron regulate the expression of a protein involved in their storage? What are the proteins? Solution In yeast there is metal-responsive transcription factors exist to modulate expression of genes that encode proteins involved in cellular uptake of copper, iron and zinc ions. 1.cellular prion protein (PrPC) with Copper 2.Regulation of Isd protein expression by iron ions. 3.In fission yeast Zinc finger protein Loz1 is required for zinc-responsive regulation of gene expression. .